1. Field of the Invention
The present invention is directed to screens for vibratory shakers, screens for classifying and/or filtering material, such screens with one or more ramped and/or raised portions over and/or through which material to be treated flows, and vibratory separators with such screens.
2. Description of Related Art
The related art section of each of the above-identified applications is incorporated here fully by reference.
The need for solids control in drilling mud used in hydrocarbon well drilling is well known in the prior art. Drilling mud, typically a mixture of clay and water and various additives, is pumped down through a hollow drill string (pipe, drill collar, bit, etc.) into a well being drilled and exits through holes in a drillbit. The mud picks up cuttings (rock) and other solids from the well and carries them upwardly away from the bit and out of the well in a space between the well walls and the drill string. At the top of the well, the solids-laden mud is discharged over a shale shaker, a device which typically has a series of screens arranged in tiered or flat disposition with respect to each other. The prior art discloses a wide variety of vibrating screens, devices which use them, shale shakers, and screens for shale shakers. The screens catch and remove solids from the mud as the mud passes through them. If drilled solids are not removed from the mud used during the drilling operation, recirculation of the drilled solids can create weight, viscosity, and gel problems in the mud, as well as increasing wear on mud pumps and other mechanical equipment used for drilling.
In some shale shakers a fine screen cloth is used with the vibrating screen. The screen may have two or more overlying layers of screen cloth. The prior art discloses that the layers may be adhered or bonded together; and that a support, supports, or a perforated or apertured plate or frame may be used beneath the screen or screens. The screen is resiliently suspended or mounted upon a support and is caused to vibrate by a vibrating mechanism, e.g. an unbalanced weight on a rotating shaft connected to the frame. Each screen may be vibrated by vibratory equipment to create a flow of trapped solids on top surfaces of the screen for removal and disposal of solids. The fineness or coarseness of the mesh of a screen may vary depending upon mud flow rate and the size of the solids to be removed.
Many screens used with shale shakers are flat or nearly flat (i.e. substantially two-dimensional). Other screens, due to corrugated, depressed, or raised surfaces are three-dimensional. U.S. Pat. Nos. 5,417,793; 5,417,858; and 5,417,859 disclose non-flat screens for use with shale shakers. These screens have a lower planar apertured plate with a multiplicity of spaced-apart apertures or openings therethrough. Undersides of troughs of undulating screening material are bonded to the apertured plate.
Vibrating screens have been employed for many years to separate particles in a wide array of industrial applications. One common application of vibrating screens is in drilling operations to separate particles suspended in drilling fluids. The screens are mounted generally horizontally on a vibrating mechanism or shaker that imparts either a rapidly reciprocating linear, elliptical or circular motion to the screen. Material from which particles are to be separated is poured onto a back end of the vibrating screen, usually from a pan mounted above the screen. The material generally flows toward the front end of the screen. Large particles are unable to move through the screen remaining on top of the screen and moving toward the front of the screen where they are collected. The smaller particles and fluid flows through the screen and collects in a pan beneath the screen.
A vibrating screen may be formed from one or more layers of wire mesh. Wire mesh is generally described with reference to the diameter of the wires from which it is woven, the number wires per unit length (called a mesh count) and the shape or size of the openings between wires. Wire mesh comes in various grades. xe2x80x9cMarketxe2x80x9d grade mesh generally has wires of relative large diameter. xe2x80x9cMillxe2x80x9d grade has comparatively smaller diameter wires and xe2x80x9cbolting clothxe2x80x9d may have the smallest diameter wire. The type of mesh chosen depends on the application. The related art section of each of the above-identified applications and patents is incorporated here fully by reference.
FIG. 34A discloses one example of a typical prior art shaker system (e.g. as shown in U.S. Pat. No. 5,190,645). A well is being drilled by a bit carried on a string of drill pipe as drilling mud is pumped by a pump into the drill pipe and out through nozzles in the bit. The mud cools and cleans the cutters of the bit and then passes up through the well annulus flushing cuttings out with it. After the mud is removed from the well annulus, it is treated before being pumped back into the pipe. The mud enters a shale shaker where the relatively large cuttings are removed. The mud then enters a degasser where gas can be removed if necessary. The degasser may be automatically turned on and off, as needed, in response to an electric or other suitable signal produced by a computer and communicated to degasser. The computer produces the signal as a function of data from a sensor assembly associated with shale shaker. The mud then passes to a desander and (or a desilter), for removal of smaller solids picked up in the well. The mud next passes to a treating station where, if necessary conditioning media, such as barite, may be added. Suitable flow controls e.g. a valve, control the flow of media. The valve may be automatically operated by an electric or other suitable signal produced by the computer as a function of the data from sensor assembly. From the treatment station, the mud is directed to a tank from which a pump takes suction, to be re-cycled through the well. The system shown in exemplary, and it will be understood that additional components of the same types (e.g. additional treatment stations) or other types (e.g. centrifuges) could be included. Such a shale shaker or vibrator separator apparatus may employ any known screen or screens and may have a single screen or combination of two or more screens, one above the other, as is well known in the art.
The present invention discloses, in at least certain embodiments, a screen assembly for a vibratory separator apparatus, the screen assembly with at least two screening members, and the at least two screen members connected by sewing material (e.g., but not limited to thread, thread-like material, staples, and/or rivets). In such a screen assembly, the at least two screening members may be a plurality of layers of screening material, and in one aspect, the plurality of layers of screening material includes at least one or two fine screen layers and a second coarse screen layer.
The sewing material may be thread; thread-like material including but not limited to, yarn, twine, string, rope and cord; rivets; and staples or any other suitable material. The sewing material may be in a pattern of spaced-apart items, knots or stitches over the surface of the screen members. One of the screen members may be a perforated plate.
In one particular embodiment of a screen assembly according to the present invention there are at least two screening members including at least two or three layers of screening material and a base, the layers of screening material sewn together to form a combined screen, the combined screen sewn to the base.
In other embodiments there is expandable material on and corresponding to a sewing stitch pattern or pattern of holes made by a needle with thread or sewing material passing through holes in the expandable material, the expandable material expanded within the holes thereby contracting the holes following extraction of a needle therefrom to inhibit tearing between holes in the screening material or of either of the at least two screening members between holes and/or to inhibit or prevent tearing between points of passage of the thread, etc. through a member or screen. In another aspect there are multiple stitches, rivets, and/or staples and/or lines thereof adjacent each other in areas of increased wear of the screen assembly.
In other embodiments there is three-dimensional screening material with a plurality of alternating ridges and troughs, with at least one series of stitches, rivets, and/or staples (or with a pattern or series thereof) on a side of a ridge (or of sides of a plurality of ridges) from a top to a bottom thereof, and the at least one series of stitches, rivets, or staples (or plurality thereof) having portions projecting out from an outer surface of the ridge or ridges for contact by solid particles flowing over the screen assembly to change direction of travel of the solid particles. The present invention also provides, in at least certain embodiments, a vibratory separator apparatus or shale shaker with a vibratory shaker device, a screen assembly mounted on the vibratory shaker device and with at least two screening members, and the at least two screen members connected by sewing material.
What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, other objects and purposes will be readily apparent to one of skill in this art who has the benefit of this invention""s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide:
New, useful, unique, efficient, nonobvious: screens and vibratory devices with such screens; screens with two or more screening members and/or screening material layers sewn together; screens with expandable material for xe2x80x9chealingxe2x80x9d or contracting the size of holes through which thread or other sewing material passes; and methods for using such screens.
Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods.
The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs. To one skilled in this art who has the benefits of this invention""s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent""s object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements.